Communications systems, and more particularly cellular radiotelephone systems such as the Global System for Mobile Communications (GSM) Digital Cellular System, are known to include a variety of services that each cellular user can subscribe to for a fee. The information regarding the identity of each user (subscriber identity) and the services that he/she subscribes to are maintained in a centralized database, for example a Home Location Register (HLR) in GSM. Each cellular provider may have one or more of its own HLRs, however, the information specific to each cellular user is contained in only one HLR. As users travel between different geographical areas, key portions of this information are transferred upon request to a local database, for example a Visited Location Register (VLR) in GSM. Each subscriber unit also contains the subscriber identity that identifies a particular user. Each time a user attempts to place a cellular phone call, the subscriber identity and the services being requested are communicated between the subscriber unit and the local VLR via the radiotelephone network. It is the responsibility of the VLR to validate the subscriber's request against subscription services that were previously arranged. This may require the VLR to request a transfer of subscription services from the subscriber's HLR. If the subscriber can be identified as a valid subscriber of the requested services, then the setup of the phone call is permitted to continue.
As is also known, each subscriber unit has a unique equipment number associated with it. Early cellular radiotelephone systems required that the subscriber only be permitted to use one radio to place phone calls. Therefore, a verification was performed to ensure that the equipment number matched the subscriber identity. This coupling of the equipment number with the subscriber identity was intended to limit fraud by preventing the same subscriber identity from being replicated. More mature radiotelephone systems (such as the GSM system) now offer the user the flexibility of transferring the subscriber identity from one radiotelephone unit to another using "smart card" technology. Additional security measures were implemented that require authentication of the subscriber identity, thus preventing the fraud of replication. Therefore, in mature radiotelephone systems such as GSM, the equipment number is not required to match the subscriber identity for fraud prevention purposes.
Current smart cards are small and lightweight (i.e. similar to a credit card), and, as the name implies, contain a computer and memory enabling subscriber information to be transferred from the smart card to the subscriber unit. As long as the smart card is inserted in the subscriber unit, the subscriber is able to communicate the subscriber identity and requested service to the radiotelephone network for validation when the subscriber desires to place a phone call. Unfortunately, the requirement for the smart card to be inserted in the subscriber unit in order to complete a phone call provides significant opportunity for the smart card to be forgotten and left in the subscriber unit. If forgotten in the subscriber unit, the above precautions taken for fraud prevention become moot if the subscriber unit ends up in the hands of an undesired user.
To the average consumer, radiotelephone services (such as cellular) offer desired services that can be expensive if more than one subscriber identity is required. The current methods described above to prevent fraud can be considered too inflexible to permit cooperating consumers to share a subscriber identity. For example, two cooperating consumers having different requirements for the time of usage of a subscriber identity could maximize the use of the subscriber identity by sharing it using a prearranged schedule. The current fraud prevention techniques prohibit efficient use of the subscriber identity.
Therefore, a need exists for a method and apparatus to temporarily transfer the subscriber identity from a subscriber unit, such as a Smart Card, to another subscriber unit, such as a radiotelephone unit, as well as a negotiated agreement for how long the receiving subscriber unit would keep the transferred subscriber identity. For that duration of time, the receiving subscriber unit would become enabled with the subscriber identity while the transmitting subscriber unit (e.g. Smart Card) would become unusable for that duration of time. Further, such a method and apparatus would permit activation times that were not immediate nor contiguous.